In reply to Joint:
Ses tres Maries (6a+) at Cala Magraner well-deserves its "Top 50" status and is awesome for the grade. The crux involves getting to a standing position on top of a blobby tufa column so should please your son.
Corrich (6a+) at Caimari also meets your spec but is hard for the grade.
At Port de Soller,
El mar del amor (6a) isn't exactly a tufa route but it does involve fantastic pumpy climbing on big holds and is also a "Top 50" route.
Hope you have a great time - if your son is leading 6a/b at age 10, he is going well!